Two types of association can be found, the association in series and the association in parallel. When it comes to the association of contacts, it is common to produce a detailed table containing all viable combinations between the contacts, called the Truth Table.
It can be observed that in the serial combination, the load can only be activated when these two contacts are activated and is known as the E function. In the parallel combination, any of the activated contacts activates the load and is called OR function.
In the association of normally closed contacts, the NF contacts can likewise be found in series and parallel. In the same way, the parallel association is called the non-E function. Thus, in the same way to change a wheel in a car that is punctured, it is necessary to know in detail the appropriate tools and their electrical commands, to understand the operation of a circuit , Knowing the appropriate elements.
The main difference is in the fact that in large panels there are buses with great capacity, which can expose people to situations of possible risks.